Assessment of pollution levels in fish and water of main basin, Lake Mariut.

Lake Mariut has suffered over the years from the untreated sewage, agricultural and industrial wastes dumped into it. Lake Mariut fish quality and quantity were adversely affected eventually being unfit for human consumption due to its poor water quality. The present study was carried out to evaluate the levels of metals in the fish caught from Lake Mariut main basin and its fitness for human consumption, and the water quality after the enforcement of the Egyptian Law for Environmental Protection (Law 4/1994). Fish and water samples were collected form Lake Mariut main basin through out the period from May to December 2000. The results showed that mercury was totally undetected in fish and water samples. The levels of Fe obtained were very low compared to previous studies. Fe and Cr contents in fish flesh were higher compared to their levels in water samples. Also Cu has shown a decrease in both fish and water samples. Zn and Cd contents in water samples have decreased compared with former studies. However, they have not changed in fish flesh. Pb content in both fish flesh and water samples has shown a great decrease compared to previous studies. The Cd and Pb mean values in fish flesh of the present study (0.81 and 0.14 mg/kg) exceeded the Egyptian Standards No. 2360/1993 value (should not exceed 0.1 mg/kg for each). The results also showed that the water quality has changed compared with previous studies. BOD has increased in north of Main Basin, east of Main Basin, South of Main Basin, and southwest of Main Basin; and deCreased in WTP effluent; and Qalaa Drain. There has been an increase in TSS, TVSS, and NO3 levels compared to pervious studies. There has been a decrease in TS, TDS, COD,hardness, and chloride levels. This decrease, especially in COD, may be attributed to the enforcement of the Egyptian Law 4/1994. The pH and alkalinity were in agreement with the values shown by previous studies except for east of Main Basin which showed higher values. The study included some recommendations aiming at improving both water quality and fish of the Main Basin.